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Prostate cancer
Prostate cancer is a form of malignancy developing in prostate, a gland in the male reproductive system. Prostate cancer tends to develop in men over the age of fifty, ranking the sixth leading cause of cancer-related death in men globally. Prostate cancer screening is becoming more prevalent, but inappropriate application of prostate cancer screening might lead to overdiagnosis and overtreatment. So it is quite important for us to have a basic yet overall knowledge about prostate cancer. Prostate specific antigen (PSA) Although remaining imperfect, Prostate specific antigen (PSA) is still the most valuable tumor marker for cancer detection. PSA, also know as γ-seminoprotein or Kallikerin-3, is encoded by klk3 gene. PSA is a Kallikrein family serine protease produced by the prostate gland epithelial cells and a component of seminal fluid necessary for ejaculation. Normal PSA value ranges from 0 – 4.0ng/ml, a PSA value>4.0ng/ml may warrant follow-up detections, depending on a series of other factors (age, ethnicity, family history of prostate cancer and so on). The most important significance of PSA is that it allows earlier detection of prostate cancer when it remains asymptomatic. Besides, the PSA has prognostic significance prior to therapy: the lower the PSA level, the more likely the cancer will be curable, the higher the PSA level, the less likely the cancer will be curable[1] . Gleason score -- prostate grading system Grading means the microscopic description of cancer aggressiveness. The Gleason Grading System is commonly used to categorize the results of prostate biopsy and evaluate the prognosis of the patient [2 ] . A Gleason score is given to the prostate cancer based on its microscopic appearance. Basically, a cylindrical sample of prostate tissue was removed via prostate biopsy. A grade (Gleason Grade or Gleason Pattern, ranging from 1 – 5, with 5 having the worst prognosis) will be assigned to the most common tumor pattern and a second grade to the next most common tumor pattern. Two grades are added together to get a final Gleason Score (or Gleason Sum). Thus the Gleason Score ranges from 2—10, with 10 having the worst prognosis[2] . Note that the same Gleason Score may indicate different tumor aggressiveness. For example, for Gleason Score 7, a Gleason 5+2 is more aggressive than a Gleason 2+5 (in Gleason 5+2, the worst prognosis pattern is more prevalent than in Gleason 2+5). Thus, cancers with a higher Gleason Score are more aggressive and have worse prognosis[3] . Single nucleotide polymorphisms (SNPs) associated with prostate cancer Three SNPs are located at the 8q24 region of the chromosome (band 24 of the q arm of chromosome 8). Although these SNPs are not close to known genes, Amundadottir et al. ''[4] and Freedman ''et al. [5] found that the DNA duplication of this region is often associated with prostate cancer cells. The duplication may increase the number of genes responsible for cell growth, thus promoting the prostate cancer progression. Besides, the risk-associated SNPs within 8q24 region might directly increase the activity of genes involved in prostate cancer [6]. References 1. Barbieri, C. E., F. Demichelis, et al. (2012). "Molecular genetics of prostate cancer: emerging appreciation of genetic complexity. " Histopathology 60(1): 187-198. 2. Borley, N. and M. R. Feneley (2008). "Prostate cancer: diagnosis and staging. " Asian Journal of Andrology 11(1): 74-80. 3. Dunn, M. W. and M. W. Kazer (2011). "Prostate Cancer Overview. " Seminars in Oncology Nursing 27(4): 241-250 4. Amundadottir LT, Sulem P, Gudmundsson J et al. ''(2006). “A common variant associated with prostate cancer in European and African populations. ” Nat. Genet. 2006; 38; 652–658. 5. Freedman ML, Haiman CA, Patterson N ''et al.(2006) Admixture mapping identifies 8q24 as a prostate cancer risk locus in African-American men. Proc. Natl Acad. Sci. USA 103; 14068–14073. 6. https://www.23andme.com/you/journal/prostate/overview/